Three-cutter bit



June 16, 1936.

F. L. SCOTT THREE- CUTTER BIT Filed Aug. 20, 1931 I I I I I I I 2Sheets-Sheet 1 FIG. 2

F'lG.1

FLOYD L. SCOTT INVENTOR ATTORNEY June 16, 1936.

F. 1.. SCOTT 2,044,549

THREE-CUTTER BIT Filed Aug. 20, 1931 2 Sheets-Sheet 2 FLOYD L-. SCOTTINVENTOR BYdQW-WM ATTORNEY Patented June 16, 1936 PATENT OFFICETHREE-CUTTER BIT Floyd L. Scott, Houston, Tex., assignor to Hughes ToolCompany, Houston, Tex., a corporation of Texas Application August 20,

SlClaims.

My invention relates to bits for use in deep well drilling.

The invention has particular application to bits of the so called rollertype having thereon cutters adapted to roll upon the bottom of the holeand cut up and disintegrate the material.

It is an object of the invention to provide a drill bit in which thecutters are secured in posi tion in such a manner as to be easilydisengaged from the head or assembled in position thereon.

I also desire to so mount the cutters on the head as to obtain aparticularly eflicient cutting action of the said cutters upon thebottom of the hole.

' I also desire to provide an assembly of cutters which will be balancedso as to roll smoothly on the bottom of the hole and rapidlydisintegrate the material.

My invention resides particularly in the con.-. struction of the headand a holder for the cutters which may be assembled in the head firmlyand securely with a minimum of manipulation.

In the drawings herewith, Fig. 1 is a side view partly in verticalsection showing the holder which I employ for the cutters. Fig. 2 is aside elevation of said holder drawn at right angles to the view shown inFig. 1. Fig. 3 is a central vertical section through the assembled drillwith the cutters in position.

In constructing my drill, I provide a head I. which is approximatelycylindrical, having an upper threaded shank 2 for engagement with thedrill collar. The lower end of the head is recessed to provide twodownwardly extending legs 3 which have notches or recesses 4 at theirlower ends to receive the shafts 5 and 6 for the outer cutters. The bithead is provided with a relatively large axial channel 1 extendingdownwardly through the shank to connect with a somewhat larger recess 8which connects with the main recess between the side legs 3.

Within the recess in the head of the drill I mount a holder shown inFigs. 1 and 2. It has an upper head 9 to fit within the recess 8, thishead being cylindrical and provided with aninner threaded socket l0.Below the head the holder is connected by means of a neck H with twodiverging arms l2 having thereon outwardly and upwardly extending shafts5 and 6 for the cutters. The lower end is forked to provide a cutterrecess l3, and the ends of the forked portion are formed with a recess Mat one side and an opening l5 at the other to receive the cutter shaft I6.

The cutter holder has on the two sides at right 1931, Serial No. 558,295

angles to the shafts 5 and 6 outwardly extending reamer blades lB--A.These blades extend outwardly to the wall of the hole and act asscraping cutters to maintain the gage of the hole. Their upper edgesextend upwardly along the side of the head 9 of the holder, and thelower edge of each leg extends to a point about even with the shafts 5and 6, the lower end being beveled forwardly at I! in the direction ofthe rotation of the bit.

When the tool is assembled, the head 9 of the holder is fitted withinthe recess 8 and a packing ring 3 is fitted within an annular recess ISin the outer wall of the chamber 8 to engage the outer surface of thehead 9, and preserve a fluid seal at that point. A locking post 20,which is of tubular construction, is inserted downwardly through theopening I in the shank of the bit, and its threaded lower end 21 isengaged within the socket ID of vthe holder. post 20 is enlarged andprovided with a lower shoulder 22'which engages with the upper end ofthe shank so as to draw the cutter holder upwardly in the head and holdit rigidly therein.

- When the holder is thus mounted in the head the flushing fluid maypass downwardly through the channel 23 in the post 20, and will find anoutlet through passages 24, 25, 26, and 21 to the pockets in which thecutters are mounted.

The cutters are shown as three in numberl There are two'outer cutters 28and 29 which cut the gage of the hole and remove the material from thebottom of the hole adjacent the wall thereof. There is also a centralcutter 30 mounted on the shaft l6 and formed to cut the material fromthe center of the hole inside the paths cut by the two outer cutters.

The cutter 28 is mounted on the upwardly inclined shaft 5 and isprovided with roller bearings 3|. The outer periphery is toothed andtapered outwardly so that when extended the surface would converge to anapex outside the Wall of the hole. Each of the outer cutters has anouter washer 32 providing a thrust surface for the outer end of thecutter and holding the roller hearings in position.

The cutter 29 is also provided with bearings 33 and washer 34. Its outersurface is toothed and tapered to converge beyond the wall of the hole.It is, however, narrower in width than is the cutter 28.

The cutter. is also provided with roller bearings. It is cylindrical atone end and tapered at 35 toward the axis of the drill. This cutterremoves the material from the center of the hole,

The upper end of the H steady the action of the outer cutters.

and its shaft I6 is offset downwardly in advance of the two shafts 5 and6. All of the cutter shafts are approximately in the same verticalplane.

When the holder with the cutters mounted thereon is clamped in positionin the head by means of the post 20, the upper ends of the two reamerblades l8-A will be received within notches 36 in 'the head of thedrill. This will serve to support the reamer blades to some extent andwill deliver a driving torque uponthe blades during the rotation of thedrill. The shape and position of the two outer cutters 28 and 29 enablethe cutters to have a particularly effective action in cutting theformation. They do not have a true rolling'motion, but will have aslipping or scraping action on the well bottom in addition to therolling, chisel action of the teeth,

and will thus remove thematerial more rapidly. The inner cutter 30extends slightly in advance of the two side cutters, and serves tocenter and noted that the larger cutter 28 at the side is arrangedadjacent the small end of the central cutter 30. I thereby get a morebalanced action of the three cutters which tends to prevent vibration,and will enable a straight hole to be drilled.

The advantages of the construction lie in the simple manner in which thecutters may be mounted in the head of the drill with a. minimum ofdifficulty, and in the particularly effective action of the cutters soformed and mounted whereby I am enabled to drill a formation withcomparatively high speed.

What I claim as new is:

1. A well drill including a head having an axial opening therein,oppositely disposed supporting legs on said head, a holder adapted tofit between said legs, opposite upwardly inclined cutter shafts on saidholder to engage in recesses in saidlegs, a shank on said holder, ahollow post extending downwardly through said head and screwed withinsaid shank, a central cutter shaft on said holder and rolling cutters onsaid shafts, the axes of said shafts being all in' the same verticalplane.

2. A well drill as set out in claim 1 and in which said holder is formedwith laterally extending reamer blades thereon.

3. A well drill including a head, a. holder fltting within a recess insaid head, means to retain said holder in said head, cuttershafts onsaid holder including two outwardly and upward- 1y projecting shafts theends of which engage within said head,and an inner inclined shaft, theaxes of said shafts lying in the same vertical plane, and rollingcutters on said shafts.

4. A well drill including a heads. holder fltting within a recess insaid head, means to retain said holder in said head, cutter shafts onsaid Itwill be holder including two outwardly and upwardly projectingshafts the ends of which engage within said head, and an inner inclinedshaft, the axes of said shafts lying in the same vertical plane, androlling cutters on said shafts, the cutters on said outer shafts beingtapered outwardly to converge outside the wall of the hole.

5. A well drill including a head, a set of three having its outer endinclined upwardly and outwardly, cutters on the two outermost of saidshafts, the peripheries of each cutter being tapered to converge at apoint outside the wall of the hole being drilled, and an intermediatecutter having its inner end tapered downwardly to extend across thelongitudinal axis of the head, said outer and intermediate cutterstogether acting to cut the full bottom of the hole.

7. An earth boring drill having a bit head with a. recess in its lowerend and a socket above the recess with a slot extending through the wallof the socket, a carrier member having a portion to fit the recess' andportions to fit the socketand slot respectively and roller cuttersmounted in the carrier with their axes in substantially the samevertical plane and arranged to cut the entire area at the bottom of thehole.-

8. A roller cutter carrier member for an earth boring, drill adapted tofit into the lower end of the'bit head of said drill, said member havinga cutter receiving recess and bearing openings for a cutter spindlecommunicating with said recess, the axis of said bearing'openings beinginclined relatively to the vertical axis of said carrier member, and ina plane radial to said vertical axis, said carrier member havingexterior lugs to fit into recesses in the bit head and a fluidpassageway in said member, substantially as described. a

9. In combination, a bit head having a cutter receiving recess therein,spindle and supporting means extending from end to end of the saidrecess in the head, interfitting lug and recessed portions between thesupporting means and the side of the head, disposed laterally of thesupporting means and above the cutters, means forsecuring the lug withinthe recessed portion, and roller cutters on the spindle means.

FLOYD L. sco'rr.

